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https://issues.apache.org/jira/browse/MAPREDUCE-1227?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12780807#action_12780807
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Allen Wittenauer commented on MAPREDUCE-1227:
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Many tasks write to HDFS as well as read, so those would need to have some way
to be paused. This is particularly interesting when thinking about a streaming
job.
But isn't the same functionality available if all of the task trackers are
down? [I've never tried it.]
> Allow JobTracker to pause task scheduling
> -----------------------------------------
>
> Key: MAPREDUCE-1227
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-1227
> Project: Hadoop Map/Reduce
> Issue Type: New Feature
> Affects Versions: 0.22.0
> Reporter: Dmytro Molkov
>
> We want to have an ability to pause task scheduling in JobTracker.
> The idea is: make job tracker still accept new jobs, but delay their running
> and do not schedule any new tasks from the currently running jobs.
> It will help for example restarting the DFS cluster without affecting jobs:
> pause execution, restart the DFS, running tasks will fail, but will not be
> scheduled until the execution is resumed, so the job does not fail.
> In general it should help fix non MR problems (DFS, network, etc.) while not
> failing running jobs and keep accepting new ones.
> What do people think of the general idea?
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